Over the years there has been an ever increasing development of different communication networks covering a vast spectrum of areas such as e.g. computer networks and telecommunication networks etc.
Communication networks may be of different scale such as e.g. Personal Area Network (PAN), Local Area Network (LAN), Campus Area Network (CAN), Metropolitan Area Network (MAN) or Wide Area Network (WAN) etc. In addition, communication networks may support and/or utilize one or several different functional relationships such as e.g. Client-Server relations and/or Peer-to-Peer relations etc. Furthermore, communication networks are usually based on one or several different topologies such as e.g. bus-networks, star-networks, ring-networks, mesh-networks, star-bus networks and/or tree topology networks etc. Similarly, communication networks may be based on wired communication and/or wireless communication. It should be emphasized that there may be no clear boundaries between different communication networks. The networks may e.g. be mixed and/or connected to each other.
Suppliers and operators of modern communication networks have become increasingly aware of the importance of communicating information between different networks. In this connection, suppliers and operators have become particularly aware of the importance of communicating information between devices which interfaces an access network with a communication network and devices which interfaces the communication network with another communication network.
A typical example is the so-called General Packet Radio Service systems (GPRS systems) defined in the standard specifications released by the 3rd Generation Partnership Project (3GPP), see e.g. www.3gpp.org. Here, special interest has been directed to the communication of information between the Serving GPRS Support Node (SGSN) which interfaces the Radio Access Network (RAN) with the Core Network (CN) and the Gateway GPRS Support Node (GGSN) which interfaces the CN with a Public Data Network (PDN).
The 3GPP standard defines how information is exchanged between the SGSN and GGSN at the Gn interface using the GTP protocol, see e.g. the technical specifications TS 23.060 “General Packet Radio Service (GPRS); Service Description; Stage 2” and TS 29.060 “General Packet Radio Service (GPRS); GPRS Tunnelling Protocol (GTP) across the Gn and Gp interface”, incorporated herein by reference.
Amongst other things the above specifications defines that the information elements MS Time Zone (MTZ) and User Location Information (ULI) may be supplied by the SGSN to GGSN as part of the four messages 1-4 below:    1) A Create PDP Context Request message sent by the SGSN,    2) An SGSN-initiated Update PDP Context Request message sent by the SGSN,    3) A Create MBMS Context Request message sent by the SGSN, or    4) An Update MBMS Context Request message sent by the SGSN.
As is well known to those skilled in the art the information element MTZ comprises information about the offset between universal time and local time where the cell phone in question currently resides. Similarly, as is well known, the information element ULI comprises information about the relevant geographic location in which the cell phone in question currently resides. An ULI may e.g. comprise the Service Area Identifier (SAI), which is used to identify an area consisting of one or more cells belonging to the same Location Area. The Service Area can e.g. be used for indicating the location of a UE (cell phone) to the CN (Core Net). This is e.g. described in the 3GPP TS 25413-750 specification. An ULI may also comprise the Cell Global Identification (CGI), which is the concatenation of the Location Area Identification and the Cell Identity. A Cell Identity is typically unique within a Location Area. The CGI can e.g. be used for indicating the location of a UE (cell phone) to the CN (Core Net). This is e.g. described in the 3GPP TS 23003-730 specification.
It should also be clarified that the PDP context (Packet Data Protocol context) can be perceived as a data structure present on both the SGSN and the GGSN which contains the session information of a subscriber when the subscriber has an active session. When a cell phone wants to use functions in a GPRS, it must first attach and then activate a PDP context, which i.a. results in a Create PDP Context Request message sent by the SGSN to the GGSN. This allocates a PDP context data structure in the SGSN which the subscriber is currently visiting and in the GGSN serving the subscribers access point. Similarly, a MBMS context is a data structure present on both the SGSN and the GGSN which contains the session information of a subscriber when the subscriber has an active multicast session using a general purpose PDP context. This is all well known to those skilled in the art.
The observant reader realizes that the four messages 1-4 mentioned above are sent for other reasons than a change in information that is related to the geographical position of the cell phone, and particularly for other reasons than a change of the value for the two information elements MTZ and ULI, i.e. for other reasons than a change in e.g. the relevant time zone or the relevant geographical location for the cell phone in question.
The benefit is that the overall signaling frequency is unaffected by a change of value in the two information elements MTZ and ULI. However, the downside is that the GGSN is not always updated with correct values of the MTZ and ULI since the two information elements are supplied to the GGSN at times that are non-correlated to the time when the information elements change values.
In the light of the above, there seems to be a need for improvements with respect to the communication of information between a SGSN which interfaces the RAN with the CN and a GGSN which interfaces the CN with a PDN. There seems to be a particular need for an improved correlation of changes in the information related to the position of a cell phone and the communication of these changes between the SGSN and the GGSN, which improvement has no or substantially no effect on the overall signaling frequency.
More generally, there seems to be a need for improvements with respect to the communication of information between a first device which interfaces an access network with a connection network and a second device which interfaces the connection network an external network. There seems to be a particular need for an improved correlation of changes in the information related to the geographical position of a wireless terminal or similar and the communication of these changes between said first and the second device, which improvement has no or substantially no effect on the overall signaling frequency.